Processes using pulsed power technology are known in the art for breaking mineral lumps. In such processes, a conduction path or streamer is created inside a formation rock to break it. An electrical potential is impressed across electrodes which contact the rock, from a high voltage electrode to a low voltage or ground electrode. At sufficiently high electric field, an arc or plasma is formed inside the rock from the high voltage electrode to the low voltage or ground electrode. The expansion of the hot gases created by the arc fractures the rock. When the streamer connects one electrode to the next, current flows through the conduction path, or arc, inside the rock. The high temperature of the arc vaporizes the rock and any water or other fluids touching or adjacent the arc. The vaporization process creates high-pressure gas in the arc zone, which expands, breaking the rock into fragments.
During such pulse powered drilling processes, it is advantageous to use, as drilling fluid, an insulating liquid that has a high relative permittivity (dielectric constant) to shift the electric fields away from the liquid and into the rock in the region of the electrodes. The insulating drilling fluid should provide high relative permittivity (dielectric constant) to provide high electric fields at the electrodes and shift a higher proportion of the electric field into the rock near the electrodes, and low conductivity to provide low leakage current during the delay time from application of the voltage until the arc ignites in the rock. Water provides high relative permittivity, but has high conductivity unless virtually free of ions, thus creating high electric charge losses. Thus, water has excellent energy storage properties, but requires extensive deionization to render it sufficiently resistive that it does not discharge the high voltage components by current leakage through the liquid. Deionized water is very corrosive and can dissolve many materials, including metals. As a result, water must be continually conditioned to maintain the high resistivity required for high voltage applications. Even when deionized, water may quickly attain sufficient conductivity that it is not suitable for long-duration, pulsed power applications.
Thus, while pulsed power drilling has the potential to dramatically change hard rock drilling due to the very fast rate of penetration (ROP) that is possible, when water becomes entrained in a pulsed power drilling fluid, for example, when water kicks are encountered or formation water from cuttings become entrained in the drilling fluid, the drilling efficiency can be undesirably reduced or the process halted. Accordingly, there is a need for systems and methods of recovering water from pulse power drilling fluids, whereby drilling efficiency can be maintained during pulse powered drilling operations. Desirably, the systems and methods allow for real time, economical removal of water at a drill site, rather than via treatment at, for example, a mud plant.